


Not In The Immortality Handbook

by mansikka



Category: Shadowhunters (TV)
Genre: Crack, Immortal Alec Lightwood, M/M, October Prompt Challenge, Tentacles, Warlock Marks (Shadowhunter Chronicles)
Language: English
Status: Completed
Published: 2019-10-09
Updated: 2019-10-09
Packaged: 2020-11-01 14:20:08
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,736
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20816561
Author URL: https://archiveofourown.org/users/mansikka/pseuds/mansikka
Summary: ...what if... Alec's warlock mark was tentacles?





	Not In The Immortality Handbook

**Author's Note:**

> Hello! This is for the prompt of _surprise tentacles_ for Tentacletober.

Everyone has had an opinion about what Alec's warlock mark might be once he's been through his immortality ceremony. Jace is insistent it will be wings, while Clary is convinced he'll have cat eyes similar to Magnus'. Isabelle keeps taunting Alec that it will be some kind of reptilian tail, making swishy, hissing noises every time she sees him and even cracking her whip with it to maximize the effect. Alex has tripped over the damn thing _twice_ now. And Max, well. Max is hoping for horns. Magnus comforts Alec through every one of these helpful suggestions, assuring him that no matter what his warlock mark might be he will love him all the same. They have promised to love one another for eternity, after all. So no matter how _unique_ his new feature, Magnus will love said feature purely because it is a part of Alec.

In the lead up to the ceremony, Alec researches extensively, hoping to find some clue about which demon to procure so that he can tailor his new mark to his liking. Not that it really works like that, apparently, and not that he's really come across a warlock mark he particularly favors, besides Magnus'. And he likes Magnus' purely because it's _him_. That, and there is something about Magnus' cat eyes that screams _bedroom_ louder than any foreplay that they have ever partaken in. One flash of amber and generally Alec is panting, or naked, or at least making plans to be both.

But if Alec were to choose a warlock mark for himself, he'd go for something understated, something a little subtle and definitely discreet. Perhaps a less brilliant tone than Catarina's beautiful blue skin, or even Lorenzo's scales if he could just tone them down a little. And while Alec loves his little sorceress, gills like Madzie's he can't imagine on his throat at all. Besides, he's hoping his runes won't disappear entirely, that they will just fade a little when they become dormant. And, he thinks, as he steps into the chamber for the ceremony still fretting over what his warlock mark might be when he steps out of it again, a well-placed gill would soon put paid to _that_.

* * *

Three weeks after the ceremony, Alec is almost disappointed that his warlock mark hasn't yet set in. He definitely _is_ a warlock; there have been some pretty vigorous rounds of testing to be sure of that. His magic is there though weak, distinctly pubescent in its nature, lurking petulantly somewhere behind his kidneys one moment then flaring out of his hands for anyone to see the next. Generally when he doesn't want it to. There is nothing that screams _premature_ more than having magic he can't control.

Usually this phenomenon is in relation to Magnus' proximity, but Alec's loved ones love him too much to tactfully point this out. Everyone but Jace, that is, who makes up for not being able to feel Alec through their parabatai rune anymore by yelling about Alec having a magic boner any chance he gets. Though according to Jace, Alec's had a magic boner ever since he first laid eyes on Magnus, and while he might have a point, that is very much not the point to be making _now_.

In any case, three weeks have passed since that ceremony, Alec is feeling mostly like himself, and since there haven't been any seismic shifts or otherworldly repercussions to him becoming a warlock, Magnus makes the executive spousal decision that they are _taking a break_. Away from the eyes and ears of everyone they know, where they can pop both magic and regular boners whenever they _like_.

And of course, because the universe is cruel, and the Angel's punishment for him abandoning his heritage surely had to come in the form of mockery, Alec's warlock mark reveals itself at the most inopportune moment. He and Magnus are enjoying the warm sea, naked, with no one on their secluded beach or for miles around. A little amorous, a little _tipsy_, and a lot handsy, they swim, and tread water, and generally indulge in being by themselves. There are kisses shared, and groans swallowed, and if the water around them feels a little _choppy_, well. Neither one of them cares, or even particularly notices.

Though when Magnus murmurs in _that_ voice that they should return to the sunlounger on the decking of their beach house to continue what they've started, Alec's warlock mark becomes… apparent. _Obvious_. It's not exactly something he can _hide_. Magnus is leading him back to the shore frequently looking down in the water; Alec thinks he's felt fish or creatures he doesn't want to think about brushing over his legs, and assumes Magnus is checking for the same. Only as they walk up the sand does it become apparent that the strange sea creature is actually _him_. Alec looks down at himself as Magnus' eyes grow wide in surprise, and an undignified squeak falls from Alec's mouth unchecked as he takes the sight of himself in.

"_Tentacles_?"

* * *

"Magnus. _Tentacles_? Seriously?" Alec asks, not that he's expecting Magnus to do anything about it.

"Well. The possibilities for warlock marks are wide and varied," Magnus says as he looks him over, clearly still trying to figure out what to say.

They've had numerous discussions on demon genetics and why it's really impossible to tell what a warlock mark might be, so Alec hopes Magnus doesn't feel _responsible_; he knew what he was getting himself into. It's just that tentacles never even crossed Alec's mind as a possible mark.

"I get that. And I understand," Alec adds; it's not as though he can put in a request for something else. And there is nothing he would ever do to give his immortality back. But _tentacles_? This certainly wasn't in the immortality handbook. Not that there was one of those, of course, which would have been _helpful_. But how could he ever have anticipated _this_?

"And at least you still have _legs_," Magnus adds with an encouraging smile.

It's not the most endearing or supportive thing to have ever fallen from Magnus' mouth in their time together, but yes, Alex thinks as he carefully flexes his tentacles, his legs are still there and functioning underneath. Though what ridiculous demon out there has both walking limbs and these things that are currently rippling around Alec like a floor-length grass skirt? Alec doesn't know, and absolutely doesn't want to see it. Though he does want to learn how to glamor his new... _things_. Right now.

"Alexander?"

Alec looks up from his _tentacles_ to see Magnus' beautifully kind, understanding smile. He feels better for it, reassured as Magnus squeezes his hand. He'll get through this. He's got through just about everything else.

"Let's go back to the house anyway," Alec says, eyeing those tentacles in suspicion at the way they just seem to dangle and bounce as they move. He huffs in surprise when he realizes he can control them, lifting one up in front of his face to inspect.

"You have suckers," Magnus says as they look at the thing together. Is he going to be able to reach things in high places with them? Grab cats out of the apothecary when they investigate Magnus' potions and threaten chaos on their world? Undo tight lids on jars when they're stubbornly stuck? The possibilities are theoretically endless.

"I need a _drink_," Alec says, and is half-tempted to test out his tentacles by sending one inside to the cocktail table Magnus has set up for their vacation, seeing if he can bring a bottle of something out. Though as he experiments with them, curls them around each other and his own legs, he's not entirely sure he trusts their mobility or strength just yet.

Magnus soothes him with kisses and then with a cocktail that is strong enough to make Alec's eyes water. _Good_. He needs that little shock to the system to adjust.

"So. How do they feel?" Magnus asks as Alec sits on the edge of the sunlounger, and Magnus makes another appear.

Alec's tentacles rearrange themselves primly around him so they won't be squished. They seem to be both sentient and controllable at his whim, which is really going to take a bit of getting used to. Currently, they seem to want to reach out and explore, sweeping over the decking feeling the grain of the wood and grittiness of the sand there. But he can also swish and flick them, and do all kinds of things, apparently, darting them out to thud against the glass of the door behind them one moment, then sneaking further afield to scoop up handfuls of sand the next. _Handfuls_, he thinks, what _is_ the correct term for scooping up a tentacle-full of something?

"Well. They don't hurt," Alec says eventually, both fascinated and mildly appalled that _this_ of all things is his warlock mark.

"Well. That's a good start."

"They just feel _there_, you know?"

"I suppose."

"Magnus. They're like limbs. They feel like they've always been there," Alec adds, standing again and prodding around where the tentacles come out of him. They form a neat little V low on his abdomen leaving his parabatai rune intact. Alec snorts with laughter at the thought of sharing _this_ little thing with Jace…

"So. You can use them?" Magnus asks as Alec sits back down, his tentacles fanning out around him.

Alec curls one around the leg of Magnus' sun lounger and tugs him closer, grinning at him in triumph. Perhaps he could have brought a bottle of scotch outside after all. "Apparently."

"What do they feel like? To touch?"

Lacking any kind of grace, Alec flops a tentacle across his own lap to inspect, stroking over the smoothness of the back of it and the ridged bumpiness of the suckers underneath. It feels _nice_, like when he's walked into a table and has to rub his shin better, or when he's back from a run when they're visiting New York and it's freezing outside, having to rub his hands over his arms to warm them up.

"Just feels like touching my own arm. Or leg."

"Really, now."

Should he touch Magnus? He'll have to get used to these things as well, after all. Alec raises a tentacle, his hesitance shimmering along the length of it. He first bumps the tip of it against Magnus' knee, and when he doesn't recoil gently wraps it around his leg.

Magnus _grins_, delighted with the gesture, tilting his head from side to side as he looks. "Alexander. Your tentacles are _beautiful_. A similar color to your eyes, though a touch more green. Soft. And so _warm_."

Alec's tentacles apparently like being praised, because they flutter up around him looking both proud and bashful. He risks a look at Magnus' face and is nothing but reassured. The same love that is always there is beaming back at him, as though these new _limbs_ are the best surprise of all.

"I'll need to learn to glamor them before we go back," Alec says as the tentacles preen and flutter around him, reflecting how, now that _he's_ got used to the idea and Magnus likes them, he's not plotting ways to make them disappear altogether.

"All in good time."

"We have a little more time here," Alec agrees, glad that these tentacles decided to reveal themselves at the beginning of their vacation. He has time to get used to them before going back home.

"And we will extend our time here by as many weeks as you need," Magnus replies with a sternness that has always made Alec shift where he's sitting for how much he _likes_ it. His tentacles seem to agree, jolting for Magnus' tone and then rippling for his attention.

Magnus' eyes crinkle with amusement for it. He delicately pats the tentacle still curled around his leg, which feels _nice_; sort of like when Magnus is resting a hand on his thigh when they watch a movie together at home. But when Magnus begins to stroke his fingertips over the back of Alec's tentacle then lifts it so he can explore the underside of it with his thumb, a deep, heavy heat begins to pool in Alec's core.

"Do that again," he groans out, wantonly parting his legs in invitation without even intending to.

Magnus raises an eyebrow and runs his thumb up the back of the tentacle, grinning with intent for the way it makes Alec stutter and shudder. "Does that feel good?"

_Good_, Alec thinks half-dazed, it's like Magnus has his cock in his grip and is stroking him with this perfect, blissful twist that is making all of his nerve endings sing at once. His _actual_ cock seems to think so, anyway, standing proudly up between all his tentacles as though it's decided to see what's going on for itself.

But then that glint in Magnus' eye turns wicked. He reaches for Alec's glass and lowers it to the floor, contemplative when he stares at him as he sits back up. Alec is already squirming with excited anticipation, even if he's not sure what Magnus is going to do next. Alec keeps their eye contact, whimpering as Magnus raises his tentacle still stroking underneath, winking at Alec before taking the tip of it into his mouth.

Alec's legs dart akimbo like a newly born calf trying to find its feet, and he's fairly sure he bleats like a goat for the _tsunami_ of arousal it sends through him. Magnus grins for his reaction, circling his tongue over one of his suckers and humming when Alec rasps out his name in response. And then he winks again, lapping his tongue over Alec's tentacle tip before sucking it into his mouth. It's the last thing Alec sees, apart from stars, before that tsunami is rising in him again. Though he is fairly sure he gets out one ineloquent _fuck_ before he finally succumbs to his pleasure and blacks out.

* * *

Alec has a spring in his step and a bounce in his (glamored) tentacles when he and Magnus return to Alicante refreshed and reinvigorated, ready to get back to work. His work environment has changed thanks to him now being a warlock, but if he can adjust to having several new limbs in only a matter of days then Alec thinks there is little he can't do.

Those _limbs_ have proven to be a very exciting addition to his life in a number of ways, not least for all the things he and Magnus can do with them together. There are practical uses for them too, of course, especially with Alec's fledgling magic still suffering from performance anxiety. He can't count the number of times he's had to shoot a tentacle out to catch whatever he's knocked over trying to get his magic to cooperate. But it's their use as a multipurpose bedroom… accessory, that both of them have really learned to appreciate. _Really_.

Alec is lost in a fond memory of some of the very clever things those tentacles can do when Jace waltzes into his office beaming at him in greeting.

"Hey," Alec says as jumps up from his desk and moves around it to hug him, "I thought you and Clary were coming here tomorrow?"

"We came through the permanent portal for a meeting. Thought we'd drop by now, see if you were around for lunch. Clary's with Magnus now," Jace adds, waving as though he's meaning somewhere out beyond Alec's office. If he strains his ear, Alec likes to think he can hear Magnus' voice.

"Sounds good," Alec says, grabbing his phone from his desk. He's more than relieved to be taking a break from work.

"We were going to maybe stay over tonight," Jace says as they leave the office, walking down the hallway to where Clary and Magnus are waiting for them with smiles. "But Magnus said something about some dinner you guys can't get out of tonight? Some… private sushi thing, or something?"

Out of sight, Alec's tentacles flutter with amusement and anticipation, and Alec fights with all that he is to hold in his smile. He clasps Jace on the shoulder since he can't form any out loud words, catching Magnus' wink of _later_ over Clary's shoulder as she steps forward for a hug.


End file.
